1. Field of the Invention
The present invention relates generally to the field of electronic circuits, and more particularly to a programmable channel select filter having high dynamic range and bandwidth.
2. Description of the Related Art
With the increased ubiquity of wireless communication devices in offices and homes, one of the most difficult challenges continues to be the design of a cost-effective, power-efficient analog transceiver. Due to its compatibility with high levels of integration, CMOS process technology has proven to be a viable candidate for a low-cost radio solution. The choice of a radio architecture, however, is of critical importance in achieving a low-power, low-cost design.
Radio architectures that require no external filtering at IF emerge as the most likely choice for simultaneously meeting the constraints of power and cost. Because there is no filtering prior to the baseband portion of such a receiver, all contiguous channels get downconverted to baseband. For this reason, the baseband channel select filter must be able to handle a large dynamic range (i.e., 60 dB at the input to the filter to pass all IEEE 802.11a blocker specifications) at bandwidths on the order of 10 MHz. In an integrated implementation, the filter frequency response must be stable with respect to variations in temperature and the manufacturing process, an additional constraint which, when combined with the dynamic range and bandwidth requirements, makes the baseband channel select filter one of the most challenging blocks in the design of an integrated direct conversion receiver.